Swim fins of various types have been used for decades by scuba divers and other swimming enthusiasts in order to gain propulsion through the water medium. Swim fins have a variety of configurations and shapes with respect to forming a foot portion and heel portion of the fin for securement to the swimmer's foot. Where the closed, instep swim fin has been utilized, it has been necessary to have a dual mold operation in order to properly produce a closed instep swim fin. That is one mold is used to mold the softer, more conformable closed foot portion and a separate mold is used to mold the more sturdy fin portion. The two independently molded pieces are then secured together.
As indicated, traditionally, the closed instep portion has been molded separate from the main fin portion with subsequent securement together to form the completed swim fin. In the prior art dual mold process, it has been necessary to have a plurality of swim fins that would accommodate various sizes of the swimmer's feet. In those instances where an open instep configuration has been utilized, they have been of the shoelace type, not having cushioned fastening for either the instep portion of the swim fin or the heel portion, and in those instances where the laced instep design has been resorted to, the fin has been singularly molded, as far as can be determined, wherein the back strap or heel portion is of the non-adjustable type.
In swim fins of the prior art, it has been necessary to have a plurality of sizes in order to accommodate various sized feet, thereby adding to the inventory cost of the fins manufacturer.
Also, in prior art fins, the closed foot portion, being of less sturdy material to provide conformability to the foot of the user has deteriorated more rapidly, over time, than the remainder of the fin, requiring that the fin be disregarded when the less sturdy or closed foot portion failed. This problem is overcome with the instant invention in that the single or integral fin is of sturdy material and the softer, conformable members of the securement means are easily replacable when, over time, they deteriorate, thereby extending the overall life of the fin.
Fins also have been proposed which have not been adequately responsive to fluid dynamic demands of a swimming fin being used in dynamic fashion in moving a swimmer through the water medium. The swim fins of some prior art patents have suggested putting cleats or knobs on heel portions of the swim fin where the user uses the fins as a steadying device, as for example, where a user fisherman is supported by an inner tube and wears the fins for propulsion purposes and the cleats or knobs are for gripping river bottoms and the like in a more efficient manner.
None of the prior art fins, as far as is known, has strategically placed protuberances projecting in a manner to create surface tension breakers to thereby create vortices to reduce the drag of the fin moving through the water. These protuberances eliminate the vacuum that slows water flowing off typical drag surfaces of a swim fin, thereby increasing propulsion.
As exemplary of some of the prior art, the following patents were uncovered in preliminary patent searches in the United States Patent Office:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 1,007,867 E. G. Halvorsen Nov. 7, 1911 2,343,468 H. L. Messinger Mar. 7, 1944 3,239,857 F. H. Gwynne Mar. 15, 1966 4,251,894 Ashley J. Hollingsworth Feb. 24, 1981 4,664,639 John D. Schneider May 12, 1987 4,832,644 Elizabeth B. Roberts May 23, 1989 4,857,024 Robert B. Evans Aug. 15, 1989 ______________________________________
A more in-depth description of each of the more pertinent patents follows:
U.S. Pat. No. 1,007,867
This patent is directed to, what may be considered, the seminal swimming device, wherein a sandal-like member is formed and to the bottom of which is attached the blade member 17, wherein adjustable straps, such as 14 and 11, using a conventional buckle is used for securing the swimming device to the foot of the swimmer.
U.S. Pat. No. 2,343,468
This patent is directed to a propulsion device for swimmers which shows the open instep portion 14 having laces for securement of the propulsion device and main body 10 around the ankle of the swimmer. The heel strap 13, which is not adjustable nor cushioned, attaches the main body 10 of the propulsion device to the heel of the swimmer.
U.S. Pat. No. 3,239,857
This patent is directed to a swim fin having, what might be termed, an open instep forming a socket 12 for containing the forepart of the foot of a swimmer. The socket member 12 is connected to a leg-encasing member 20 and a snap button, such as 23, is utilized to attach the leg-encasing portion 20 to the swimmer.
U.S. Pat. 4,251,894
This patent is directed to a swim fin, wherein the heel portion has a self-adjusting strap wherein the fin has a closed foot pocket 10.
U.S. Pat. No. 4,664,639
This patent is directed to a foot fin utilized by a fisherman or the like and has secured to the foot fin a plurality of spaced cleats 15 to aid the fisherman walking on a surface of a river bottom or the like.
U.S. Pat. No. 4,832,644
This patent is directed to a swimming fin which has an adjustable heel strap 20 which is provided with a heel protection device comprising a heel protector 14 of polymer foam material so that chafing of the heel of the swimmer does not occur or is substantially reduced.
U.S. Pat. No. 4,857,024
This patent relates to the ubiquitous type of swim fin having movable tips with an adjustable heel strap 62 which may utilize fastening means 64 which may also be a velcro fastener.